Sash balance mechanism



Fewo, 6, 1951 Filed Jan. 11, 1946 FIG. I

L. A. MACKLANBURG ET'AL SASH BALANCE MECHANISM 2 Sheets-Sheet 1 FIG. 2

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BY W 0. Wi/M/ ATTORNEY L. A. MACKLANBURG ET AL SASH BALANCE MECHANISM Feb 6, 1951 Filed Jan. 11, 1946 Patented Feb. 6, 1951 SASH BALANCE. MECHANISM Louis A. Macklanburg and Harry B. Foresman, Oklahoma City, Okla.

Application Janu-aryrll, 1946, Serial No.\640,'581

2 Claims. 1

My invention relates .to apparatusfor balancing, or in .otherwords for automaticallyholdi'ng. adjustably stationary, vertically slidable. window sashes.

The mechanism of the present inventionis intended to supplant the conventional sash-cord, sash-pulleys and sash weights, and .to .consequently eliminate the necessity. of theusual. sash weight channels in the. window. frame.

A principal object of. the invention is to provide.

a mechanically operated sash. balancing. mecha nism, which is operatively housed. withina longitudinal furrow or groove. ploughed int-he. vertical edgeof the sash.

Anothertobject. is to. provide .a. mechanism of this class which is simple toinstall. has few. movingparts to become worn. or to get. out. of order,v and which is comparatively-cheap. to manufacture.

In the past, there have been. automatically operated sash balancing mechanisms. which rely upon springs tosupplantthe usual. sash weights. Some such mechanisms rely upon long-stretch coiled springs to overcome .or supporttheweig-ht of the sash. Others have used. laterally. movable spring loaded plates or plungers-to retardmovement of the sash through friction. Thapresent invention falls more or less under the first classification, since it balances .thaweight of the sash through the use of .a helical spring. However; the present invention overcomes some of. the. impractical features found inmost spring balances of nonfrictiona1 type.

In most sash balances ofthis class, the coil spring must be capable of stretching a distance substantially equal to the permitted. travel of the sash. The result is that there is eitheralack.

of sufficient spring'tension at one end ofthe travel, or excessive tension'atthe other end, or both.

It is an object of the present invention to so mount a coil spring with relation toa sash,. that the spring only stretches a distance substant ally equal to one-half of the sash travel, andin which.

the point at which the spring is anchored tothe window frame, is automatically shifted. during movement of the sash, so as to partially com- Another object is to provide a spring sash ba ance of the type above disclosed, which may be installed without removing the sash from the window frame.

Other objects will be apparent from the following description when taken in conjunction with the. accompanying two sheets of drawings, wherein;

Figure 1 is a fragmentary elevational. view of the balance mechanism operatively installed be tween. a window frame and av vertically slidable sash, the sash being shown in dotted lines at; the lower end of its permitted travel;

Figuref2 is a similar view showingv the sash at the upper end of its permitted travel; Figure 3. is a fragmentary perspective view showing a sash provided with a vertical groove in one edge for operatively receiving the balance mechanism;

Figure 4 is an enlarged detail ofa traveling friction block used in one. embodiment ofthe invention;

Figure 5. is a similar View showing a different embodiment of traveling frictionmember; and

Figure 6 is an enlarged. vertical sectional view detailing a portion of the mechanism.

Like characters of reference designate like parts accommodate the balancing mechanism of the present invention, the only requirement is .that theouter edgeof the vertical side rail-5. of the sash 4 be providedwith an elongatedgroove 6 which extends throughout the entire length of the rail, and has open upper and lower ends as shown (Fig. 3).

The sash balance mechanisrmper se, of the present invention, includes:

An angle fitting it, which is anchoredto the lower end of the sash rail 5, has an upeturned end extending outwardlyinto the open lower end of the groove 6. A he ical retrieving spring ll lies within the groove 6 and has its lower end attached to the fitting It. The upper end of the spring I l is attached to the lower looped end it of a sheet metal stirrup or cage. I 3, having fiat sides M and I5. Between the Sides. [4 and I5 is anchored, by a pin I6, a solid block I'I having a cylindrically rounded lower end portion I8 (Fig. 4). The block Il may be of any suitable material such as wood, plastic or metal, and the stirrup l3 and block I! are sufflciently small in cross-sectional dimension to freely move upwardly and downwardly in the groove ii. The stirrup l3 and block I'I might well be termed a traveling block. I

With one of its ends attached firmly to the window frame member I adjacent the top member 2, is a ribbon-like flexible member It which extends downwardly along the frame member I, passes through the stirrup l3 beneath the rounded lower end I8 of the block ll, passes upwardly in the groove 6 in the sash d, and is attached by a fitting (Fig. 6) to the upper end of the sash. The flexible member I9 may be of any suitable material such as annealed metal, woven fabric or leather, and its end is preferably attached to the fitting 20 by a rivet or rivets 2 I.

The fitting 2G is preferably made of resilient or spring metal, and has a depending arcuate or bowed portion 22 which lies in the sash groove 6. The fitting 20 also has a flat horizontal portion 23, which lies upon the upper end of the sash rail 5 and is attached thereto by a nail 24. The flexible member I9, therefore, is resiliently held in spaced relation to the valley surface of the groove 6 by the bowed portion 22 of the fitting.

When the sash is at, or is adjacent the upper end of its travel (Fig. 2), the spring E I is in substantially collapsed condition, although the flexible member I9 remains taut due to the action of the spring. The sash is there held stationary. As

, the sash is'lowered, the block ll which is sus- I greater than one-half the maximum distance the sash is permitted to travel. This arrangement eliminates excessive spring tension when the spring is at its fullest elongation. The arrangement also eliminates the necessity of manually overcoming excessive spring tension during downward movement of the sash. The maximum required stretch of the spring is illustrated in Fig. 1.

Since the spring tension is the greatest when the sash is at the lower end of its travel, there might be a tendency for light weight sash to be unseatecl by this tension. This tendency is defeated by the bowed portion 22 of the fitting 20. The portion 22 acts to urge the stirrup I3 toward wedging engagement with the window frame member I, as the fitting 26 approaches the stirrup. Friction is therefore supplied where the spring is at its tightest.

While the drawings and the above description have dealt with the installation and operation of the device upon only one side of the sash, it is to be understood that in most cases a similar installation will be made on the opposite side thereof. The two devices operating in unison make it possible to utilize lighter springs than would be necessary should only one spring be used.

In Figure 5 is illustrated a slightly difierent embodiment or form of traveling block than that shown inFig. 4:. V

In the embodiment of Fig. 4, the flexible member I9 slides around the lower end of the solid 4 block I1, and the friction of the member around th block I'I tends to stabilize the sash against being moved upwardly by the spring from a stationary position. V V

In the embodiment of Fig. 5, a cylindrical roller or sheave 25 is journalled for rotation in the side members I4 and I5 of the stirrup, and the flexible member I! is passed beneath this roller. This arrangement eliminates the frictional wear of the block I! and the flexible member I9 which is encountered in the embodiment of Fig. 4. However, the desirable sash stabilizing friction is also eliminated.

As a means for providing this desired sash stabilizing friction, a cylindrical body 26 of elastic or resilient material, such as rubber, is placed above the stirrup I3 between the two vertical extents of the flexible member I9. The body 26 is of slightly greater diameter than that of the roller 25, and therefore it assumes a slightly ovate form when placed in position as shown. The body 25 is not anchored in any manner, but is confined to its position only by the presence of the sides of the groove 6 in the sash. I

When the sash is moved vertically, the flexible member E9 simultaneously bears against the opposite sides of the body 26, Withone extent of.

the member l9 travelling upwardly and the other moving downwardly. Since the body 26 was forced to assume an ovate form when placed between the two extents of the flexible member I9, it maintains a constant frictional engagement with the member I9. Simultaneous movement of the two extents of the member I 9 therefore have a kneading action upon the body 26 with the inherent resilience of the material of the body constantly resisting the deformation thereof. The

1. In a sash balancing mechanism adapted. for

use in a window frame having a vertically slidable window sash therein, said sash balancing mechanism comprising: a flexible ribbon-l ke member having one end attached to the upper portion of the frame, and having its other end connected to the upper portion of the sash with slack in the member provided intermediate said ends; a helical retrieving spring having its lower end anchored to the lower portion of the sash; a substantially U-shaped stirrup having its legs pointing upwardly and having its central portion connected to the upper end of the spring; and a friction block carried between .the legs of the stirrup and slidably engaged within the slack portion of the flexible member.

2. In a sash balancing mechanism adapted for use in a window frame having a vertically slidable window sash therein, said sash balancing mechanism comprising: a helical spring attached to the lower portion of the sash and extending upwardly along a vertical edge thereof; a looplike fitting carried by the upper end of the spring; a flexible ribbon-like member having one end attached to the upper portion of the frame,

v 2,540,746 5 a 6 said member extending downwardly through said REFERENCES CITED fitting 1 upwardly to t upper portion of the The following references are of record in the sash; means for anchoring the member to said me of this patent: upper sash portion; and a block of frictional ma- UNITED STATES PATENTS terial associated with said fitting for offering frictional resistance to the sliding movement of Number Name t said flexible member with relation to the fitting. 7 402 Mulder 21, 9 1,760,226 Appleby May 27, 1930 LOUIS MACKLANBURG- 2,279,600 Tappan Apr. 14, 1942 HARRY FORESMAN- is 2,336,406 Kreuscher Dec. 7, 1943 

